GigaSpaces Integration with Kafka

Introduction

Apache Kafka is a distributed publish-subscribe messaging system. It is designed to support persistent messaging with a O(1) disk structures that provides constant time performance even with many TB of stored messages.
Apache Kafka provides High-throughput even with very modest hardware, Kafka can support hundreds of thousands of messages per second. Apache Kafka supports partitioning the messages over Kafka servers and distributing consumption over a cluster of consumer machines while maintaining per-partition ordering semantics. Many times Apache Kafka is used to perform parallel data load into Hadoop.

This pattern integrates GigaSpaces products with Apache Kafka. GigaSpaces’ write-behind data grid operations to Kafka making it available for the subscribers. Such could be Hadoop or other data warehousing systems using the data for reporting and processing.

GigaSpaces-Kafka Integration Architecture

The GigaSpaces-Kafka integration is done via the SpaceSynchronizationEndpoint interface deployed as a Mirror service. It consumes a batch of data grid operations, converts them to custom Kafka messages and sends these to the Kafka server using the Kafka Producer API.

The GigaSpace-Kafka protocol is simple and represents the data and its Space operation. The message consists of the Space operation type (Write, Update , rRemove, etc.) and the actual data object. The data object itself could be represented either as a single object or as a Space Document with key/values pairs (SpaceDocument).

Since a Kafka message is sent over the wire, it should be serialized to bytes in some way. The default encoder utilizes Java serialization mechanism which implies Space classes (domain model) to be Serializable.

By default, Kafka messages are uniformly distributed across Kafka partitions. Please note, even though Space operations appear ordered in SpaceSynchronizationEndpoint, it doesn’t imply the correct ordering of data processing in Kafka consumers. See the following diagram:

Getting Started

Download the Kafka Example

You can download the example code from here.
Unzip into an empty folder.

The example is located under <project_root>/example. It demonstrates how to configure Kafka persistence and implements a simple Kafka consumer that pulls data from Kafka and stores in HsqlDB.

Space Documents

To configure a Kafka topic for a SpaceDocuments or Extended SpaceDocument, the property KafkaPersistenceConstants.SPACE_DOCUMENT_KAFKA_TOPIC_PROPERTY_NAME should be added to the SpaceDocument. Here is an example.

Kafka Consumers

The Kafka persistence library provides a wrapper around the native Kafka Consumer API for the GigaSpace-Kafka protocol serialization. Please see com.epam.openspaces.persistency.kafka.consumer.KafkaConsumer, for example of how to use it under <project_root>/example module.

Customization

Kafka persistence was designed to be extensible and customizable.

If you need to create a custom protocol between a GigaSpaces product and Kafka, provide an implementation of AbstractKafkaMessage, AbstractKafkaMessageKey, and AbstractKafkaMessageFactory.

If you would like to customize how Space operations are sent to Kafka or how the Kafka topic is chosen for a given entity, provide an implementation of AbstractKafkaSpaceSynchronizationEndpoint'.

If you want to create a custom serializer, look at KafkaMessageDecoder and KafkaMessageKeyDecoder.

The Kafka Producer client (which is used under the hood) can be configured with a number of settings; see the Kafka documentation.